Chronic proliferative diseases are often accompanied by profound angiogenesis, which can contribute to or maintain an inflammatory and/or proliferative state, or which leads to tissue destruction through the invasive proliferation of blood vessels. (Folkman, EXS 79:1–8, 1997; Folkman, Nature Medicine 1:27–31, 1995; Folkman and Shing, J. Biol. Chem. 267:10931, 1992).
Angiogenesis is generally used to describe the development of new or replacement blood vessels, or neovascularisation. It is a necessary and physiological normal process by which the vasculature is established in the embryo. Angiogenesis does not occur, in general, in most normal adult tissues, exceptions being sites of ovulation, menses and wound healing. Many diseases, however, are characterized by persistent and unregulated angiogenesis. For instance, in arthritis, new capillary blood vessels invade the joint and destroy cartilage (Colville-Nash and Scott, Ann. Rheum. Dis., 51, 919,1992). In diabetes (and in many different eye diseases), new vessels invade the macula or retina or other ocular structures, and may cause blindness (Brooks et al., Cell, 79, 1157, 1994). The process of atherosclerosis has been linked to angiogenesis (Kahlon et al., Can. J. Cardiol. 8, 60, 1992). Tumor growth and metastasis have been found to be angiogenesis-dependent (Folkman, Cancer Biol, 3, 65, 1992; Denekamp, Br. J. Rad. 66, 181, 1993; Fidler and Ellis, Cell, 79, 185, 1994).
The recognition of the involvement of angiogenesis in major diseases has been accompanied by research to identify and develop inhibitors of angiogenesis. These inhibitors are generally classified in response to discrete targets in the angiogenesis cascade, such as activation of endothelial cells by an angiogenic signal; synthesis and release of degradative enzymes; endothelial cell migration; proliferation of endothelial cells; and formation of capillary tubules. Therefore, angiogenesis occurs in many stages and attempts are underway to discover and develop compounds that work to block angiogenesis at these various stages.
There are publications that teach that inhibitors of angiogenesis, working by diverse mechanisms, are beneficial in diseases such as cancer and metastasis (O'Reilly et al., Cell, 79, 315, 1994; Ingber et al., Nature, 348, 555, 1990), ocular diseases (Friedlander et al., Science, 270, 1500, 1995), arthritis (Peacock et al., J. Exp. Med. 175, 1135, 1992; Peacock et al., Cell. Immun. 160, 178, 1995) and hemangioma (Taraboletti et al., J. Natl. Cancer Inst. 87, 293, 1995).
Angiogenesis signals result from the interaction of specific ligands with their receptors. The Tie1 and Tie2 receptors are single-transmembrane, tyrosine kinase receptors (Tie stands for Tyrosine kinase receptors with immunoglobulin and EGF homology domains). Both were recently cloned and reported by several groups (Dumont et al., Oncogene 8:1293–1301, 1993; Partanen et al., Mol. Cell Biol. 12:1698–1707, 1992; Sato et al., Proc. Natl. Acad. Sci. USA 90:0355–9358, 1993).
Based upon the importance of Tie2 receptors in angiogenesis, inhibition of Tie2 kinase activity is predicted to interrupt angiogenesis, providing disease-specific therapeutic effects. Recently, Lin et al. (J. Clin. Invest. 100:2072–2078, 1997) has shown that exogenously administered soluble Tie2 receptor inhibited angiogenesis and cancer growth in animal models. Thus inhibition of Tie2 receptors by other means, such as inhibition of Tie2 receptor kinase activity, is expected to have therapeutic benefit in proliferative diseases involving angiogenesis.
The current application teaches the novel finding that compounds of specific structure can inhibit the kinase activity of the Tie2 receptor, block its signal transduction and thus may be beneficial for proliferative diseases via inhibition of signals for angiogenesis.